Energy attenuation apparatus for a conduit conveying liquid under pressure, system incorporating same, and method of attenuating energy in a conduit

ABSTRACT

An energy attenuation apparatus for a system conveying a liquid under pressure is provided. The apparatus includes a liquid-conveying unit or the like that includes three chambers disposed in series. At least one of the chambers contains no tube. A first tube is disposed in one of the chambers and has a first end connected to and in fluid communication with an inlet or outlet end of its chamber. A second, free end of the tube is spaced by an open gap from the outlet or inlet end of such chamber. The tube has at least one aperture in the free end and/or on the peripheral surface thereof for providing fluid communication between the tube and its chamber. A second tube can be disposed in the remaining chamber.

RELATED APPLICATIONS

[0001] This application is a continuation-in-part application ofcopending application Ser. No. 09/370,658 filed Aug. 6, 1999, which is acontinuation-in-part application of Ser. No. 08/977,081 filed Nov. 24,1997.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] This invention relates to a new energy attenuation apparatus fora conduit that is adapted to convey liquid under pressure, as well as asystem incorporating such a device and a method of attenuating energy ina conduit. The invention is particularly suitable for placement in aconduit conveying liquid under pressure for the attenuation of pressurepulses in the liquid, especially in the hydraulic system of the powersteering unit of a vehicle. The invention would also be suitable forother hydraulic fluids.

[0004] 2. Prior Art Statement

[0005] In hydraulic systems where the operating liquid is circulated bya pump, the pulsations of pressure that are generated by the pump aretransmitted through the conduits and result in noise and/or vibrationbeing produced by the hydraulic liquid. In the case of power steeringfluid in vehicles, such noise and/or vibration is caused, for example,when vehicles are being parked or unparked at idle or very low speeds ofmovement thereof, such as by barely moving into and out of a parkingspace or the like while the wheels of the vehicle are being turned bythe power steering mechanism thereof. In particular, substantial noiseand/or vibration (shudder) can be produced in such a situation when thepower steering fluid passes through the power steering mechanism fromthe fluid pump to the effective steering structure. Further backgroundinto this area can be obtained from U.S. Pat. No. 3,323,305, Klees,whereby this U.S. patent is being incorporated into this disclosure bythis reference thereto.

[0006] Devices are known for suppressing noise in exhaust gas mufflers.For example, U.S. Pat. No. 4,501,341, Jones, provides two side branchresonators, while U.S. Pat. No. 4,371,053, Jones, provides for anapertured tube in a gas muffler housing. Systems are also known forcontrolling the resonation of pressure waves in fuel injection systems.For example, U.S. Pat. No. 5,168,855, Stone, passes fluid through checkvalves that are provided with a flow restriction either directly thereinor in a bypass line. U.S. Pat. No. 5,509,391, DeGroot, provides a spoolvalve assembly for controlling flow between inlet and outlet ports.

[0007] Applicants are not aware of any teaching of transferring flow ofliquid under pressure from one tube to another as a means of suppressingenergy, especially where at least one of the tubes is provided with atleast one hole.

SUMMARY OF THE INVENTION

[0008] It is therefore an object of the present invention to provide animproved apparatus, system and method for attenuating energy in aconduit that conveys liquid under pressure.

[0009] This object is realized pursuant to the energy attenuationapparatus of the present invention by providing a liquid-conveying meansin which the apparatus is disposed, wherein the liquid-conveying meansincludes three chambers disposed in series, with one of the chamberscontaining no tube, i.e. being empty; a first tube is disposed in asecond one of the chambers, wherein an annular space is formed betweenthe inner peripheral surface of the liquid-conveying means and the outerperipheral surface of the first tube, wherein the first tube has a firstend connected to and in fluid communication with an inlet or outlet endof the second one of the chambers, wherein the first tube has a second,free end that is spaced by an open gap from the outlet or inlet end ofthe second one of the chambers, and wherein the first tube has at leastone aperture in the free end and/or on the peripheral surface thereoffor providing fluid communication between the first tube and the secondone of the chambers; and a second tube can be disposed in a third one ofthe chambers, wherein an annular space is formed between the innerperipheral surface of the liquid-conveying means and the outerperipheral surface of the second tube, wherein the second tube has afirst end connected to and in fluid communication with an inlet oroutlet end of the third one of the chambers, wherein the second tube hasa second, free end that is spaced by an open gap from the outlet orinlet end of the third one of the chambers, and wherein the second tubehas at least one aperture in the free end and/or on the peripheralsurface thereof for providing fluid communication between the secondtube and the third one of the chambers.

[0010] Accordingly, it is an object of this invention to provide a novelenergy attenuation device having one or more of the novel features ofthis invention as set forth above or hereinafter shown or described.

[0011] Another object of this invention is to provide a new systemincorporating such an energy attenuation device, such a system havingone or more of the novel features of this invention as set forth aboveor hereinafter shown or described.

[0012] Another object of this invention is to provide a new method ofattenuating energy in a conduit conveying liquid under pressure, such amethod having one or more of the novel features of this invention as setforth above or hereinafter shown or described.

[0013] Other objects, uses, and advantages of this invention areapparent from a reading of the specification in conjunction with theaccompanying schematic drawings, which form a part thereof and wherein:

BRIEF DESCRIPTION OF THE DRAWINGS

[0014]FIG. 1 illustrates a simplified automotive power steering systemthat incorporates one exemplary embodiment of the energy attenuationapparatus of this invention;

[0015]FIG. 2 is a cross-sectional view of one exemplary embodiment ofthe energy attenuation apparatus of this invention;

[0016]FIG. 3 is a cross-sectional view of a second exemplary embodimentof the energy attenuation apparatus of this invention;

[0017]FIG. 4 is a cross-sectional view of a third exemplary embodimentof the energy attenuation apparatus of this invention;

[0018]FIGS. 5a and 5 b are enlarged cross-sectional views of arestrictor for use with an energy attenuation apparatus of thisinvention;

[0019]FIG. 6 is a view similar to that of FIG. 2 of a modified energyattenuation apparatus of this invention;

[0020]FIG. 7 is a cross-sectional view of a fourth exemplary embodimentof the energy attenuation apparatus of this invention;

[0021]FIG. 8 is a cross-sectional view of a fifth exemplary embodimentof the energy attenuation apparatus of this invention;

[0022]FIG. 8a shows a modification of the embodiment of FIG. 8;

[0023]FIG. 9 is a view similar to that of FIG. 4 of a modified energyattenuation apparatus of this invention;

[0024]FIG. 10 is a cross-sectional view of a sixth exemplary embodimentof the energy attenuation apparatus of this invention;

[0025]FIG. 10a shows a modification of the embodiment of FIG. 10;

[0026]FIGS. 10b to 10 g are cross-sectional views taken through the hosemeans and the tubes;

[0027]FIG. 11 is a modification of the embodiment of FIG. 10;

[0028]FIG. 12 is a cross-sectional view of a further exemplaryembodiment of the energy attenuation apparatus of this invention;

[0029]FIG. 13 is a view similar to that of FIG. 12 of a modified energyattenuation apparatus of this invention;

[0030]FIG. 14 is a view similar to that of FIG. 12 of a modified energyattenuation apparatus of this invention;

[0031]FIG. 15 is a view similar to that of FIG. 12 of a modified energyattenuation apparatus of this invention;

[0032]FIG. 16 is a view similar to that of FIG. 12 of a modified energyattenuation apparatus of this invention;

[0033]FIG. 17 is a view similar to that of FIG. 12 of a modified energyattenuation apparatus of this invention;

[0034]FIG. 18 is a view similar to that of FIG. 12 of a modified energyattenuation apparatus of this invention;

[0035]FIG. 19 is a view similar to that of FIG. 12 of a modified energyattenuation apparatus of this invention;

[0036]FIGS. 20 and 21 show various embodiments of tuning cable or tubearrangements for use in conjunction with the energy attenuationapparatus of this invention;

[0037]FIG. 22 is a partial block diagram showing one arrangement for usein conjunction with the present invention; and

[0038]FIG. 23 is a cross-sectional view of a further exemplaryembodiment of an energy attenuation apparatus of this invention.

DESCRIPTION OF PREFERRED EMBODIMENTS

[0039] While the various features of this invention are hereinafterillustrated and described as providing an energy or sound attenuationdevice for an automotive power steering system, it is to be understoodthat the various features of this invention can be utilized singly or invarious combinations thereof to provide an energy attenuation device forother systems that convey liquid, especially liquid under pressure.

[0040] Therefore, this invention is not to be limited to only theembodiment illustrated in the drawings, because the drawings are merelyutilized to illustrate one of the wide variety of usages of thisinvention.

[0041] Referring now to the drawings in detail, FIG. 1 illustrates asimplified automotive power steering system. During operation, the powersteering pump 11 generates pressure ripples that are transmitted throughtubing T, such as steel tubing, to the pressure hose assembly orpressure line 12, the power steering gear 13, the return hose assemblyor return line 14, and the reservoir 15, and finally flow back to thepump 11 itself by means of the supply line 16. It should be noted thatrather than being separated by a hose or similar conduit, the reservoir15 and the pump 11 could actually be a single unit.

[0042] In order to greatly reduce noise, such as from resonance, forexample in the pressure line 12 or in the return line 14, and therebyeliminate or at least greatly reduce the power steering noise orvibration generated by the power steering pump 11, the energyattenuation device of this invention, which is indicated generally bythe reference numeral 20, is disposed either in the pressure line 12,between the steering pump 11 and the gear 13, or in the return line 14,between the gear 13 and the reservoir 15 or the pump 11. In addition, itwould also be conceivable to dispose the energy attenuation device 20 inboth the pressure line 12 and the return line 14. Various exemplaryembodiments of the energy attenuation device 20, and components andarrangements thereof, are illustrated in FIGS. 2-23 and will bedescribed in detail subsequently.

[0043] The energy attenuation device 20 of this invention can, asindicated previously, be disposed in the pressure line 12 and/or thereturn line 14 of the system of FIG. 1. However, as illustrated in theexemplary embodiments of FIGS. 24 and 6-19, the energy attenuationdevice 20 can also be disposed in a separate hose section that is inturn disposed in such pressure line 12 or return line 14.

[0044] As can be seen from the embodiment of the energy attenuationdevice 20 illustrated in FIG. 2, two separate apertured tubes 21 aredisposed in the chamber 22 formed in the hose section orliquid-conveying means 23. In particular, an inlet tube 21 a isconnected to the inlet end 25 of the chamber 22, whereas an outlet tube21 b is connected to the outlet end 26 of the chamber 22. The tubes 21a, 21 b are disposed in the chamber 22 in such a way that not only arethe free ends 27 and 28 thereof spaced from one another by an open gap,but the outer peripheral surfaces 30,31 of the inlet and outlet tubes 21a and 21 b are spaced from the inner peripheral surface 32 of the hoseor conduit means 23 in such a way that an annular space 33 isrespectively provided about the outer peripheral surfaces 30,31 of eachof the tubes 21 a, 21 b. By means of at least one, preferably several,holes 34 provided in each of the outer peripheral surfaces 30, 31 of theinlet and outlet tubes 21 a, 21 b, liquid entering the hose means 23 viathe tubing T can exit the inlet tube 21 a into first the annular space33 and then part of the remainder of the chamber 22, from where it canflow through further holes 34 into the outlet tube 21 b and from thereout of the hose means 23 into the right-hand tubing T. Depending uponwhether the free ends 27, 28 of the tubes 21 a, 21 b are opened orclosed, all or only part of the liquid in the pressure line 12 or returnline 14 will pass through the holes 34 out of the inlet tube 21 a andinto the outlet tube 21 b. Details concerning the open or closed stateof the free ends 27, 28 of the tubes 21 a, 21 b will be discussedsubsequently.

[0045] In the embodiment of the energy attenuation device 20 illustratedin FIG. 2 the hose section 23, which is made, for example, of rubber orother elastomeric material, is disposed in the pressure line 12 or thereturn line 14 and is connected to the tubing T, in a fluid conveyingmanner, via respective couplings 36 and connectors, which can be of thetype illustrated in FIGS. 11-19 and described in applicants' U.S. Pat.No. 6,279,613, the disclosure of which is hereby incorporated into thisapplication by this reference thereto.

[0046] As indicated previously, the free ends 27, 28 of the inlet tube21 a and outlet tube 21 b can be either open or closed off. Severalpossibilities exist for configuring the free ends 27 and 28. Forexample, both free ends could be open, or both could be closed. Inaddition, the free end 27 of the inlet tube 21 a could be open while thefree end 28 of the outlet tube 21 b could be closed. On the other hand,the opposite arrangement could also be provided whereby the free end 27of the inlet tube 21 a would be closed and the free end 28 of the outlettube 21 b would be open.

[0047] Although the embodiment illustrated in FIG. 2 provides for asingle chamber 22 with the free ends 27, 28 of the inlet and outlettubes 21 a, 21 b facing each other at the middle of the hose mixingregion of the chamber 22, it has been found according to the teachingsof this invention that other configurations are also possible. Forexample, reference is now made to FIG. 3, wherein another configurationof the energy attenuation device of this invention is shown and isindicated generally by the reference numeral 20A, wherein parts thereofsimilar to the energy attenuation device 20 of FIG. 2 are indicated bylike reference numerals that where appropriate are followed by thereference letter A.

[0048] The embodiment of the energy attenuation device 20A illustratedin FIG. 3 differs from that shown in FIG. 2 in that the chamber 22A isdivided by a restrictor 38 into an inlet chamber portion 39 and anoutlet chamber portion 40. An enlarged view of the restrictor 38 isshown in FIGS. 5-5 b; the inner diameter of the restrictor is less thanthe inner diameter of the hose means 23A. It should be noted that therestrictor 38 is disposed in the hose means 23A, for example bycrimping, in such a way that communication between the chamber portions39 and 40 can be only via the passage means, i.e. the reduced diameterportion, of the restrictor. The free end 27 of the inlet tube 21 a isspaced from the restrictor 38 in the inlet chamber portion 39, while thefree end 28 of the outlet tube 21 b is spaced from the restrictor 38 inthe outlet chamber portion 40. Thus, with the energy attenuation device20A, liquid that is exiting the inlet tube 21 a, either entirely or atleast partially via the holes 34, will enter the inlet chamber portion39, will then flow through the reduced diameter portion of therestrictor 38, will enter the outlet chamber portion 40, and then atleast partially via the holes 34 will enter the outlet tube 21 b. Asdiscussed in conjunction with the energy attenuation device 20 of FIG.2, the free ends 27, 28 of the inlet and outlet tubes 21 a, 21 b can beeither both open, both closed, or only one open and the other closed.

[0049] In the embodiment of the energy attenuation device 20A the inletand outlet tubes 21 a, 21 b are connected to the inlet and outlet ends25, 26 of the respective inlet chamber portion 39 or outlet chamberportion 40. However, it would also be possible to connect the inlet andoutlet tubes 21 a, 21 b directly to the restrictor 38 instead of to theinlet and outlet ends of the chamber. Such connection can again beeffected via the aforementioned connectors of applicants' U.S. Pat. No.6,279,613. For example, reference is now made to FIG. 4, wherein anotherenergy attenuation device of the present invention is shown and isindicated generally by the reference numeral 20B.

[0050] In the embodiment of the energy attenuation device 20B, the freeends 27, 28 of the inlet and outlet tubes 21 a, 21 b face away from oneanother, namely toward the inlet and outlet ends of the inlet chamberportion 39 and outlet chamber portion 40 respectively, and are spacedfrom such inlet and outlet ends. Again, the free ends 27, 28 of theinlet and outlet tubes 21 a, 21 b can both be opened, can both beclosed, or only one can be opened with the other being closed.

[0051] As indicated above, the two separate apertured tubes 21 a, 21 bare each provided with at least one hole 34 in the outer peripheralsurface thereof. Pursuant to some presently preferred embodiments, it iscontemplated that each of the apertured tubes 21 will have a pluralityof such holes 34. Several arrangements of these holes 34 are possible.For example, the holes 34 can be arranged in a longitudinal direction inone or more rows of such holes, either aligned or offset relative to oneanother, or can also be disposed in a random manner about the peripheralsurfaces 30, 31 of the tubes 21 a, 21 b. FIG. 6 shows one such possiblearrangement. In this embodiment, the apertured tube 21 a on the inletside has two holes 34 disposed 180□ from one another. In contrast, theapertured tube 21 b on the outlet side has two rows of four holes 34,with the rows being disposed 90□ from one another, and with the holes ofone row being offset in a longitudinal direction from the holes of theother row. In addition, the free end of the tube 21 a is open while thefree end of the tube 21 b is closed. It is to be understood thatalthough the arrangement of FIG. 6 has been illustrated in conjunctionwith a tube arrangement similar to that of FIG. 2, such an arrangementof the holes 34 would be possible for any of the embodiments previouslydescribed.

[0052] In addition to the number and arrangement of the holes 34 in theapertured tubes 21, it will be appreciated that other system parameterswill affect the noise attenuation that can be achieved. For example, theratios and dimensions of the components of the device relative toanother can be varied. Although in the illustrated embodiments thelengths of the inlet and outlet tubes 21 a, 21 b are shown as being thesame, the lengths of these two tubes can also differ from one another.In addition, the inlet and outlet tubes 21 a, 21 b can extend overvarying proportions of the chamber 22. In the embodiment of the energyattenuation device 20 shown in FIG. 2, it is presently contemplated thateach of the apertured tubes 21 will extend over more that one fourth ofthe length of the chamber 22 of the hose means 23. Similarly, in theembodiments of FIGS. 3 and 4, it is contemplated that each of theapertured tubes 21 a, 21 b will extend over more than one half of thelength of its respective inlet or outlet chamber portion 39 or 40.

[0053] Although the previously illustrated embodiments provide for aninlet tube 21 a and an outlet tube 21 b that are both provided withholes 34, it has been found according to the teachings of this inventionthat only one of the tubes 21 a, 21 b need be provided with such holes.In addition, rather than providing a fairly wide space in the chamber 22of the hose means 23 between the free ends 27, 28 of the inlet andoutlet tubes 21 a, 21 b, a narrow gap could also be provided betweensuch free ends. For example, reference is now made to FIG. 7, whereinanother energy attenuation device of the present invention is shown andis indicated generally by the reference numeral 20C.

[0054] In the embodiment of the energy attenuation device 20C, the freeends 27, 28 of the inlet and outlet tubes 21 a, 21 b are separated fromone another by only a narrow gap 42, for example a gap having a width ofapproximately {fraction (1/32)}-⅛ of an inch. In addition, only one ofthe tubes, namely the inlet tube 21 a, is provided with holes 34, forexample two such holes that are disposed 90□ or 180□ from one another.The narrow gap 42 between the free ends 27, 28 of the inlet and outlettubes 21 a, 21 b has in this embodiment been illustrated as beingdisplaced toward the outlet end of the chamber 22C. However, such narrowgap could also be disposed closer to the inlet end of the chamber 22C,in which case the outlet tube 21 b would be longer than the inlet tube21 a. Furthermore, although the holes 34 have been illustrated as beingdisposed approximately half way between the inlet and outlet ends of thechamber 22 c, such holes 34 could be disposed at any desired locationalong one of the inlet or outlet tubes 21 a, 21 b. In addition, ratherthan being disposed on the inlet tube 21 a, such holes 34 could also bedisposed on the outlet tube 21 b. Furthermore, any desired arrangementof the holes 34 is possible, and the embodiment of FIG. 2 could also bemodified to include the narrow gap 42 of the embodiment of FIG. 7,wherein both the inlet tube 21 a and the outlet tube 21 b could again beprovided with holes 34.

[0055] In the embodiment of the energy attenuation device 20Billustrated in FIG. 4, a respective tube is disposed in each of theinlet and outlet chamber portions 39, 40. However, it has been foundaccording to the teachings of this invention that only one of thechamber portions need contain a tube. For example, reference is now madeto FIG. 8, wherein another energy attenuation device of the presentinvention is shown and is indicated generally by the reference numeral20D.

[0056] In the embodiment of the energy attenuation device 20D, only oneof the chambers contains a tube, with the other chamber being empty. Inthe illustrated embodiment, it is the inlet chamber portion 39 thatcontains no tube, and therefore forms the empty chamber 55, while theoutlet chamber portion 40 contains a tube, namely the outlet tube 21 b,which is illustrated as being connected to the restrictor 38 and havingits free end 28 spaced from the outlet end of the chamber 40. The outlettube 21 b could also be connected to the outlet end of the chamber 40and have its free end spaced from the restrictor 38. To provide fluidcommunication from the inlet chamber portion 39, i.e. the empty chamber55, via the restrictor 38 to the outlet chamber 40, the outlet tube 21 bis provided with at least one aperture. For example, the free end 28 ofthe outlet tube 21 b could be open, while the peripheral surface of thetube 21 b could be provided with no apertures. Alternatively, theperipheral surface of the tube 21 b could be provided with at least onehole (see FIG. 8a), and the free end 28 of the tube could be open orclosed off.

[0057] Rather than the inlet chamber portion 39 being empty, the emptychamber 55 could be formed by the outlet chamber portion 40, with thechamber 39 then being provided with the inlet tube 21 a, which could beconnected to the inlet end of the chamber 39 or to the restrictor 38.The empty chamber 55 could have a length of from ½ inch to 12 inches oreven greater, and in one specific embodiment has a length of 140 mm,with the tube, for example the outlet tube 21 b, having a length of 100mm in a chamber portion that has a length of 140 mm..

[0058] In the embodiment of the energy attenuation device 20B of FIG. 4,the inlet and outlet tubes 21 a, 21 b are provided with holes on theperipheral surfaces thereof. However, it has been found according to theteachings of this invention that it would be possible to provide noholes on the peripheral surfaces of the inlet and outlet tubes and tohave only the free ends of these tubes open. For example, reference isnow made to FIG. 9, wherein another energy attenuation device of thepresent invention is shown and is indicated generally by the referencenumeral 20E.

[0059] In the embodiment of the energy attenuation device 20E, the freeends 27, 28 of the inlet and outlet tubes 21 a, 21 b are open, while theperipheral surfaces of these tubes are not provided with any holes. Inthe illustrated embodiment, both the inlet and outlet tubes 21 a, 21 bare connected to the restrictor 38. However, it would also be possibleto connect the inlet and outlet tubes to the inlet and outlet openingsof their respective chambers, with the free ends of these tubes thenbeing spaced from the restrictor 38, similar to the embodimentillustrated in FIG. 3. Again however only the free ends would be openwhile the peripheral surfaces of the inlet and outlet tubes 21 a, 21 bwould have no holes.

[0060] The ratio of the length of the inlet tube 21 a to the length ofthe outlet tube 21 b could range from 1:5 to 5:1, and in one specificembodiment of the present invention both have the same length of 154 mm,with both the inlet and outlet chamber portions having a length of 194mm.

[0061] In this embodiment, the inlet and outlet tubes 21 a, 21 b aremade of polymeric material.

[0062] Although in the previous embodiments the energy attenuationdevices have been illustrated as being provided with at most twochambers, it has been found according to the teachings of this inventionthat the hose or conduit means could be provided with three chambers.For example, reference is now made to FIGS. 10-19 and FIG. 23, whereinother energy attenuation apparatus of the present invention are shownand are indicated generally by the reference numerals 20F to 20P.

[0063] In the embodiment of the energy attenuation apparatus 20F, afurther restrictor 57 is provided such that an intermediate chamber 58that contains no tubes, in other words an empty chamber, is formedbetween the inlet and outlet chamber portions 39, 40. Although in theillustrated embodiment the inlet and outlet tubes 21 a, 21 b areconnected directly to the restrictors 38, 57, with the free ends 27, 28thereof being spaced from the inlet and outlet portions of therespective inlet and outlet chamber portions 39, 40, it would also bepossible to connect the inlet and outlet tubes 21 a, 21 b directly tothe inlet and outlet portions of their respective chambers, with thefree ends of the tubes then being spaced from the respective restrictors38, 57.

[0064] In addition, the free ends 27, 28 of the inlet and outlet tubes21 a, 21 b could be open, while the peripheral surfaces of the tubescould be provided with no holes. Alternatively, the peripheral surfaceof at least one of the inlet and outlet tubes 21 a, 21 b could beprovided with holes (see FIG. 10a) while the free ends of the tubescould be open or closed off.

[0065] Rather than the third, empty chamber 58 being provided betweenthe inlet and outlet chamber portions 39, 40, the empty chamber 58 couldalso be disposed after the second chamber 59, as indicated in theembodiment of the energy attenuation apparatus 20G illustrated in FIG.11, with the tubes 61 and 62 being disposed in the first or inletchamber 39 and in the second chamber 59 respectively. Further exemplaryembodiments of three chamber configurations will now be described.

[0066] In the embodiment of the energy attenuation apparatus 20Hillustrated in FIG. 12, the empty chamber 58 is the first chamber, whilethe tube 61 is disposed in the second chamber 59 and the tube 62 isdisposed in the third chamber 64.

[0067] Whereas in the embodiment illustrated in FIG. 12 the ends of thetubes 61 and 62 are open, and the peripheral surfaces thereof areprovided with no holes, the embodiment of the energy attenuationapparatus 20I illustrated in FIG. 13 shows that one of the tubes, herethe tube 61 in the second chamber 59, can be provided with one or moreholes 34. In the embodiment of the energy attenuation apparatus 20Jillustrated in FIG. 14, both of the tubes 61 and 62 are provided withone or more holes 34. In both the embodiment of FIG. 13 and of FIG. 14,the ends of the tubes 61 and 62 can either be open or closed.

[0068] The embodiment of the energy attenuation apparatus 20Killustrated in FIG. 15 is similar to the embodiment illustrated in FIG.10. In this embodiment, the tube 61 is disposed in the first chamber 39,while the tube 62 is disposed in the third chamber 64. The middlechamber 58 is an empty chamber. In this embodiment of FIG. 15, the tubes61 and 62 are again shown as having no holes, with the free ends thereofbeing open. However, it is to be understood that again the peripheralsurfaces of one or both of the tubes 61 and 62 could be provided withholes 34, while the free ends of the tubes 61 and 62 could be open orclosed.

[0069] In the embodiment of the energy attenuation apparatus 20Lillustrated in FIG. 16, the tubes 61 and 62 are disposed in the firstchamber 39 and the second chamber 59 respectively, with the thirdchamber 58 being the empty chamber. Again, the peripheral surfaces ofthe tubes 61 and/or 62 could be provided with holes 34 if desired.

[0070] The embodiment of the energy attenuation apparatus 20Millustrated in FIG. 17 is similar to the energy attenuation apparatus20H of FIG. 12. However, in the embodiment of the energy attenuationapparatus 20M, instead of being separated by restrictors, the chambers58, 59 and 64 are separated by respective tubing T. Although in theembodiment of FIG. 17 the empty chamber 58 is shown as being the firstchamber, the empty chamber could also be the second chamber 59 or thethird chamber 64, similar to the showing of the embodiments of FIGS. 15and 16. Furthermore, again the peripheral surfaces of the tubes 61 and62 could be provided with holes 34, and the free ends of these tubescould be opened or closed.

[0071] In the embodiment of the energy attenuation apparatus 20Nillustrated in FIG. 18, an arrangement similar to that of the embodimentof FIG. 12 is illustrated. However, in the embodiment of FIG. 18, thefirst chamber 58 and the second chamber 59 are separated by a tubing Trather than a restrictor, while the second chamber 59 and the thirdchamber 64 continue to be separated by the restrictor 57. It is to beunderstood that rather than the first and second chambers beingseparated by tubing T, these two chambers could be separated by arestrictor while the second chamber 59 and the third chamber 64 areseparated by tubing T.

[0072] In the embodiments of the energy attenuation apparatusillustrated in FIGS. 11-18, the end of the tubes shown as beingconnected, either to the liquid-conveying means or to the restrictor ortubing, has always been the left hand end. However, it is to beunderstood that at least for some of the tubes the situation could bereversed, in other words, with the right hand ends being connected. Byway of example, in the embodiment illustrated in FIG. 19, the tube 61,rather than being connected to the restrictor 38, is connected at theright hand end, in a fluid communicating manner, to the restrictor 57,with the left hand or free end of the tube 61 being opened and spacedfrom the restrictor 38. Similarly, the tube 61 is connected at theoutlet end of the chamber 64, with the open free end of the tube 62being spaced from the restrictor 57 Although in the embodiment of FIG.19 the empty chamber 58 has been shown as being the first chamber, thisempty chamber could also be either the second chamber or the thirdchamber. In addition, the peripheral surfaces of the tubes 61 and 62could, if desired, be provided with holes 34, and the free ends of thesetubes could be opened or closed.

[0073] The ratio of the length of the inlet tube 21 a to the length ofthe outlet tube 21 b could range from 1:5 to 5:1 or even greater. Theempty, for example intermediate, chamber 58 has an effective length offrom ½ inch to 24 inches or even greater. In one specific embodiment ofthe present invention, the intermediate chamber 58 has a length of 200mm, and the inlet and outlet tubes 21 a, 21 b both have the same lengthof 115 mm, with both the inlet and outlet chamber portions having alength of 155 mm.

[0074] The restrictors 38, 57 can, for example, have a length of from 41to 46 mm.

[0075] The hose or liquid-conveying means 23 can be a single section ofrubber and/or other elastomeric or plastic material that is connected tometal, especially stainless steel, tubing T by means of the couplings36, or the hose means can also comprise separate hose sections that areinterconnected by restrictor means or tubing. Furthermore, the hosemeans 23 may be made of a single layer or of a plurality of layers ofthe aforementioned rubber and/or plastic. The hose means 23 may also besuitably reinforced to withstand comparatively high fluid pressures. Thehose means 23 could furthermore be made of metal, such as stainlesssteel. In addition, although the tubes 21, 61, 62 have been illustratedas being disposed in the hose means 23, such hose or conduit means canactually be a continuation of the tubing T, or a separate tubingsection, again made of metal. In contrast, the tubes can be made ofpolymeric material, especially tetrafluoroethylene fluorocarbon resins,fluorinated ethylenepropylene resins, or polyamide; the apertured and/oropen tubes could also be made of metal, especially stainless steel, orrubber. Thus, the tubes can be either flexible or rigid. For the sake ofconvenience, the cross-sectional views of FIGS. 10b to 10 g through thehose means and the tubes to show the various material possibilitiestherefore have been taken in conjunction with the embodiment of FIG. 10.It is, however, to be understood that these views apply to the otherillustrated and described embodiments as well. Where the conduit meansis a hose of rubber, other elastomeric material, or metal, it can, forexample, have an inner diameter of {fraction (3/8)} inch to {fraction(1/2)} inch or larger. The diameter of the inlet and outlet tubes 21 a,21 b, and of the tubes 61 and 62, will depend largely upon the diameterof the conduit means 23. For example, if the conduit means has an innerdiameter of {fraction (3/8)} inches, the inlet and outlet tubes couldhave an outer diameter of {fraction (5/16)} inches or less. Similarly,if the conduit means has an inner diameter of ½ inches, the inlet andoutlet tubes could have an outer diameter of {fraction (3/8)} inches orless. The annular space between the outer peripheral surface of a tubeand the inner peripheral surface of the liquid-conveying means can rangefrom {fraction (1/32)} to {fraction (3/18)} of an inch. The length ofthe conduit means, and hence of the inlet and outlet tubes, can varydepending upon need and available space and can range from 2 inches to12 feet.

[0076] As indicated previously, the open ends of the tubes of theembodiments illustrated in FIGS. 10-19 and 23 are spaced from the endsof their respective chamber. Such spacing is presently contemplated asranging from 10 mm to 500 mm, and in presently preferred embodimentsranges from 30-40 mm.

[0077] The size and shape of the holes 34 can also vary. For example,circular holes 34 can have a diameter of {fraction (1/16)} inches, ⅛inches, etc. If the holes 34 have an oval shape, pursuant to onespecific embodiment of the present invention the dimension of such holescan be {fraction (1/8)} inches in width by ½ inches in length.

[0078] The restrictor means 38, 57 has an inner diameter that is lessthan the inner diameter of the hose means 23. In addition, the innerdiameter of the restrictor 38, 57 can be equal to, greater than or lessthan the inner diameter of the inlet and outlet tubes. The restrictormeans can be made of any suitable material, including metal, rubber andpolymeric material (see FIGS. 5a and 5 b).

[0079] Where tubing T is provided between chambers, such tubing can havea length of from 1 to 50 inches.

[0080] The inventive energy attenuation device can also be used inconjunction with a variety of other sound and vibration attenuationdevices, which are then also disposed in the pressure line 12 and/orreturn line 14. For example, a ¼ wave cable tuning assembly can beprovided, for example by disposing a steel cable in a further hosesection. Examples of such tuning cable arrangements in further hosesections are shown in FIGS. 20 and 21, wherein FIG. 20 shows a singletuning cable 44 disposed in the further hose section or conduit means45, whereas FIG. 21 shows two separate tuning cables 44 disposed in afurther hose section or conduit means 46. An example of a known tuningcable is disclosed in the aforementioned patent to Klees, U.S. Pat. No.5,323,305, which patent has been incorporated into this disclosure. Thetuning cable arrangements in the conduit means 45 or 46 can be disposedin series with the inventive energy attenuation device, or can bedisposed in parallel therewith. Other sound and vibration attenuationdevices are also known. For example, reference is made to U.S. Pat. Nos.4,611,633 (Buchholz et al), 5,172,729 (Vantelini) and 5,201,343(Zimmermann et al) whereby such U.S. patents are also being incorporatedinto this disclosure by this reference thereto. Furthermore, aspring-type energy attenuation device as disclosed in applicants'copending U.S. patent application Ser. No. 08/853,770 could also beprovided, whereby the disclosure of such application is alsoincorporated into this disclosure by this reference thereto. One or moreof such other attenuation devices could also be used in conjunction withthe energy attenuation apparatus 20-20O of the present invention. Forexample, FIG. 22 shows an arrangement where the tubing T is split intobranches 48, each of which leads to an energy attenuation device that isschematically indicated by one of the boxes 50 or 51. This parallelarrangement can either be disposed in series with one of the inventiveenergy attenuation apparatus 20-20O, or one of the boxes 50, 51 cancontain an inventive energy attenuation apparatus while the other boxcontains a known attenuation apparatus Furthermore, both boxes 50 and 51can contain the same or different ones of the inventive energyattenuation apparatus 20-20O. It should be noted that two or more of theinventive energy attenuation apparatus could be disposed in seriesand/or in parallel with one another, or even with an empty hose section.For example, reference is now made to FIG. 23, which illustrates anotherenergy attenuation apparatus 20P of the present invention. Thisembodiment shows an empty hose section 66 in series with one of theother inventive embodiments previously described, such as, by way ofexample, the embodiment 20D of FIG. 8. The empty hose section 66 couldalso be disposed upstream of the other inventive embodiment, or even inparallel therewith. Furthermore, the embodiment of the energyattenuation apparatus 20P of FIG. 23 could also be similar to theembodiment of FIG. 12, wherein all three chambers are disposed in seriesin a liquid-conveying means. The middle chamber would then be separatedfrom the third or empty chamber 66 by a further restrictor similar tothe restrictor 57. In addition, whereas in this embodiment the chambersare separated from one another by restrictors, two or all three of thechambers could be separated from one another by respective tubing, ortwo of the chambers could be separated by tubing and the other two by arestrictor.

[0081] In view of the foregoing, it can be seen that this invention notonly provides a new energy attenuation device, but also this inventionprovides a new method for attenuating energy in a fluid conveyingsystem.

[0082] While the forms and methods of this invention is now preferredhave been illustrated and described as required by the Patent Statute,it is to be understood that other forms and method steps can be utilizedand still fall within the scope of the appended claims, whereby it isbelieved that each claim sets forth a novel, useful and unobviousinvention within the purview of the patent statute.

What we claim is:
 1. An energy attenuation apparatus for a systemconveying a liquid under pressure, said apparatus comprising: aliquid-conveying means in which said apparatus is disposed, wherein saidliquid-conveying means includes three chambers disposed in series,wherein one of said chambers contains no tubes; a first tube disposed ina second one of said chambers, wherein an annular space is formedbetween an inner peripheral surface of said liquid-conveying means andan outer peripheral surface of said first tube, wherein said first tubehas a first end connected to and in fluid communication with an inlet oroutlet end of said second one of said chambers, wherein said first tubehas a second, free end that is spaced by an open gap from said outlet orinlet end of said second one said chambers, and wherein said first tubehas at least one aperture in said free end and/or on said peripheralsurface thereof for providing fluid communication between said firsttube and said second one of said chambers; and a second tube disposed ina third one of said chambers, wherein an annular space is formed betweenan inner peripheral surface of said liquid-conveying means and an outerperipheral surface of said second tube, wherein said second tube has afirst end connected to and in fluid communication with an inlet oroutlet end of said third one of said chambers, wherein said second tubehas a second, free end that is spaced by an open gap from said outlet orinlet end of said third one of said chambers, and wherein said secondtube has at least one aperture in said free end and/or on saidperipheral surface thereof for providing fluid communication betweensaid second tube and said third one of said chambers.
 2. An energyattenuation apparatus according to claim 1, wherein said chambers areseparated from, and communicate with, one another via respectiverestrictor means.
 3. An energy attenuation apparatus according to claim1, wherein said chambers are separated from, and communicate with, oneanother via respective tubing means.
 4. An energy attenuation apparatusaccording to claim 1, wherein said first and second ones of saidchambers are separated from, and communicate with, one another via arestrictor means, and said second and third ones of said chambers areseparated from, and communicate with, one another via a tubing means. 5.An energy attenuation apparatus according to claim 1, wherein said firstand second ones of said chambers are separated from, and communicatewith, one another via a tubing means, and said second and third ones ofsaid chambers are separated from, and communicate with, one another viaa restrictor means.
 6. An energy attenuation apparatus according toclaim 1, wherein said chamber that contains no tube can be any one ofsaid three chambers.
 7. An energy attenuation apparatus according toclaim 1, wherein said free ends of first and second tubes are open toprovide said aperture therein, and said peripheral surfaces of saidfirst and second tubes have no apertures.
 8. An energy attenuationapparatus according to claim 1, wherein at least one of said peripheralsurfaces of said first and second tubes is provided with at least oneaperture, and said free ends of said first and second tubes are open orclosed.
 9. An energy attenuation apparatus according to claim 1, whereinsaid free ends of said first and second tubes are spaced by an open gapranging from 10 to 500 mm from said outlet or inlet end of theirrespective chamber.
 10. An energy attenuation apparatus according toclaim 1, wherein a first one of said chambers contains no tube, whereinsaid first tube is disposed in an intermediate one of said chambers, andwherein said second tube is disposed in a third one of said chambers.11. An energy attenuation apparatus according to claim 10, wherein saidchambers are separated from, and communicate with, one another via arespective restrictor means or tubing means, wherein said first ends ofsaid tubes are connected to respective ones of said restrictor means ortubing means, and wherein said free ends of said tubes are spaced fromsaid outlet end of the chamber in which said tube is disposed.
 12. Anenergy attenuation apparatus according to claim 10, wherein saidchambers are separated from, and communicate with, one another viarespective restrictor means or tubing means, wherein said first ends ofsaid tubes are connected to the outlet end of the chamber in which saidtube is disposed, and wherein said free ends of said tubes are spacedfrom respective ones of said restrictor means or said tubing means. 13.An energy attenuation apparatus according to claim 1, wherein anintermediate one of said chambers contains no tube, with said first tubebeing disposed in a said first one of said chambers and said second tubebeing disposed in a third one of said chambers.
 14. An energyattenuation apparatus according to claim 13, wherein said chambers areseparated from, and communicate with, one another via a respectiverestrictor means or tubing means, wherein said first ends of said tubesare connected to respective ones of said restrictor means or tubingmeans, and wherein said free ends of said tubes are spaced from saidoutlet end of the chamber in which said tube is disposed.
 15. An energyattenuation apparatus according to claim 13, wherein said chambers areseparated from, and communicate with, one another via respectiverestrictor means or tubing means, wherein said first ends of said tubesare connected to the outlet end of the chamber in which said tube isdisposed, and wherein said free ends of said tubes are spaced fromrespective ones of said restrictor means or said tubing means.
 16. Anenergy attenuation apparatus according to claim 1, wherein a third oneof said chambers contains no tube, wherein said first tube is disposedin a first one of said chambers, and wherein said second tube isdisposed in an intermediate one of said chambers.
 17. An energyattenuation apparatus according to claim 16, wherein said chambers areseparated from, and communicate with, one another via a respectiverestrictor means or tubing means, wherein said first ends of said tubesare connected to respective ones of said restrictor means or tubingmeans, and wherein said free ends of said tubes are spaced from saidoutlet end of the chamber in which said tube is disposed.
 18. An energyattenuation apparatus according to claim 16, wherein said chambers areseparated from, and communicate with, one another via respectiverestrictor means or tubing means, wherein said first ends of said tubesare connected to the outlet end of the chamber in which said tube isdisposed, and wherein said free ends of said tubes are spaced fromrespective ones of said restrictor means or said tubing means.
 19. Anenergy attenuation apparatus for a system conveying a liquid underpressure, said apparatus comprising: a liquid-conveying means in whichsaid apparatus is disposed, wherein said liquid conveying means includesthree chambers disposed in series, wherein two of said chambers containno tube; and a tube disposed in a third one of said chambers, wherein anannular space is formed between an inner peripheral surface of saidliquid-conveying means and an outer peripheral surface of said tube,wherein said tube has a first end connected to and in fluidcommunication with an inlet or outlet end of said third one of saidchambers, wherein said tube has a second, free end that is spaced by anopen gap from said outlet or inlet end of said third one of saidchambers, and wherein said tube has at least one aperture in said freeend and/or on said peripheral surface thereof for providing fluidcommunication between said tube and said third one of said chambers. 20.A method of attenuating energy in a system conveying a liquid underpressure, including the steps of: disposing in said system aliquid-conveying means that includes three chambers disposed in series,wherein at least one of said chambers contains no tube; disposing in atleast one of said chambers a tube such that an annular space is formedbetween an inner peripheral surface of said liquid-conveying means andan outer peripheral surface of said tube; connecting a first end of saidtube to and in fluid communication with an inlet or outlet end of itschamber; spacing a second, free end of said tube by an open gap fromsaid outlet or inlet end of said chamber; and providing said tube withat least one aperture in said free end and/or on said peripheral surfacethereof for providing fluid communication between said tube and itschamber.